The present invention relates to dehumidifier control systems which prevent the buildup of ice on the refrigerant coils in the dehumidifier.
Home dehumidifiers typically consist of a humidistatically controlled compressor for circulating a refrigerant, such as Freon (Trademark of E. I. duPont de Nemours & Co., Inc.), through sets of evaporator and condenser coils. An electric fan, also controlled by the humidistat, blows ambient air over the coils which causes moisture in the air to condense on the cold evaporator coils. The condensation then either drips into a pan or flows through a drain hose.
When a dehumidifier is in a cold environment, such as may be encountered in an unheated basement, if the ambient temperature falls low enough (e.g. below 65.degree. F.), the evaporator coil surface temperature may drop below the freezing point. Ths causes ice to form on the evaporator coil creating an insulating layer which interferes with the dehumidification. Eventually, the ice builds up to the point where the air flow through the coil becomes completely blocked at which time the dehumidification process ceases. The dehumidifier then must be manually shut off in order for the temperature of the evaporator coil to rise above the freezing point allowing the ice to melt.